Differential Enrichment of Trace and Major Elements in Biodegraded Oil: A Case Study from Bohai Bay Basin, China

Inorganic elements in crude oil have been used the reconstruction of sedimentary environment and oil–oil (source) correlations; however, effect biodegradation on these has not investigated sufficiently. In this study, 14 oils from Miaoxi Sag Bohai Bay Basin, eastern China, were analyzed using molecular markers, trace elements, major to determine inorganic elements. The markers indicated that are low maturity stage derived similar parent materials lacustrine source rocks. high-sulfur came a more reductive saltier compared with low-sulfur oil. subjected varying degrees biodegradation. concentrations Mg, Ca, Mn, Fe, Be, Sc, Rb, Sr, Zr, Pb, Th, U increased significantly throughout process, while Na, K, Ti, Al, Cr, Zn, Cs, Nb, Ba, Hf, Tl considerably only during intense (PM < 4). P, Li, V, Co, Ni, Cu, Ga, Sn, Ta correlated level V/Ni, V/Co, Ni/Co, Cr/V, Sc/V, Th/U ratios affected by when PM ≥ 4. Several ratios, including Mg/P, Ca/P, Mn/P, Fe/P, proposed as favorable indicators Differential enrichment is associated effects organic acids generated oil–water–rock interactions reservoir.